2 digitisers - one inverted to record the lower exposure levels with higher precision, the output from both digitisers combined. The idea was apparently patented by Eric Fossum, (no ref) and the patent now owned by Aptina (no ref), so Nikon would have to agree terms if they wanted to use it. Alternatively, could use a switchable digitiser for better precision?

I don't recognize this as something I invented....actually I am not sure exactly what you mean. The idea of the same signal being split and one going through a high gain channel and the other through a low gain channel and then both being digitized was used in scientific CCDs some time ago (I am not sure who did that first), just in case that is what you are talking about.